Articles having a fine concave-convex structure with a cycle which is equal to or less than the wavelength of visible light on the surface thereof have been known to show an antireflective effect, a lotus effect, and the like. In particular, a fine concave-convex structure called a moth-eye structure has been known as effective antireflection means because a refractive index continuously increases from the refractive index of air to the refractive index of the material of the article.
An article having a fine concave-convex structure on one surface or both surfaces has been proposed as an antireflection article (Patent Documents 1 and 2).
However, since the convex portions of the fine concave-convex structure are very small, the mechanical strength is low and the fine concave-convex structure on the surfaces of the antireflection article has insufficient abrasion resistance. Therefore, when the antireflection article is used for a protective filter with an antireflective function in a display device, and when a person or an object touches the surface thereof, the fine concave-convex structure is easily damaged and the antireflective function deteriorates.
It is preferable to reduce the aspect ratio of the convex portion (the ratio of the height of the convex portion and the width of the bottom of the convex portion) in order to increase the mechanical strength of the convex portion, which forms the fine concave-convex structure.
However, when the aspect ratio of the convex portion is low, the difference between the maximum reflectance and the minimum reflectance in the visible light range increases, that is, the reflectance has wavelength dependency, such that it is difficult to sufficiently suppress reflection of light with some wavelengths.